Lens dilemma for you all.

I currently own a sigma 18-200mm lens which takes some good photos despite being a bit slow in low light...but, should I opt for the Canon 70-200mm L or go for the lens I wanted to get the 100-400mm L..

I am looking to take photos of wildlife etc which drew me to the 100-400 but the 70-200L with 1.4x may offer this to me also.

Your thoughts please

its funny that you just posted this because i was considering that lens (Sigma)... i have been reading all over the web and gettin mixed reviews but most seem to come back to the same conclusion that more than one lens is needed... because of performance considerations of the sigma... what are you feelings about the sigma? shoudl I even spring for it??

IF its mostly for wildlife the 400f5.6L may be a better bet then the zoom.
Rob.

I took all of these with it and like it a lot...just getting the L glass bug

http://www.dpetc.com/a​rtist.php?id=CentreLig​ht

For wildlife, I think you'd be happier with the 100-400.

Agreed. You could also consider the 300 F4 L IS and a 1.4x TC for extra reach. I like shooting without a tripod so the IS swung it for me over the similarly priced 400 F5.6 L. I find 200 mm way too short for most wildlife.

What is your budget?
A wonderful lens is the Sigma 120-300 f/2.8, but it is quite expensive ($2200 at B&H)...
Attach a TC on it and you get a 420 f/4...

I would kill for that lens!
Did I just say that?

The 100400IS is going to be your best overall wildlife lens. The 400f5.6 is your best "mostly birding" lens.

300 is not really long enough for wildlife. Actually nothing ever is long enough. I'd vote for the 400/5.6 L myself. Had one and it was great. Light and easy to handhold and for following birds in flight.

A little off topic...

I have both the 70-200IS2.8L and the 100-400IS5.6L

Both are superb. (The 100-400 is definately the nature lens)

Why o why o why did canon design one with a push pull zoom and one with a twist ? Does this annoy other users ? The twist is smoother...

I don't personally buy Sigma any more... but have you checked out their options ?

I would allso go for the 100-400L,super lens.

I also own both a 70-200f2.8L (non-IS) and a 100-400f4.5-5.6L (dust trumpet), and they are both superb lenses. I hate the push-pull of the 100-400, and the inconsistency (on mine at least) of the tension adjustment on the sliding zoom. That said, I still love both of these lenses, and find that the 100-400 produces consistently stellar focus, clarity and contrast in longer-range shots.
Here is an example of a long shot at 400mm in early morning light:

http://sdwike.smugmug.​com/photos/25280714-L.jpg

It's hard to appreciate the clarity and detail in a reduced-size jpg, but even at this low-res, I think it shows that lenses ability.

100-400. It doesn't make a lot of sense to get a lens that you expect to use with a teleconverter most of the time when there's an excellent alternate readily available. And 200 with a 1.4 will leave you short compared to 400.

...and if you really consider using an 18-200 -as I do- you should consider the Tamron lens.
According to tests, the optical quality seems to be significantly better than the Sigma.

This is the first time I've heard that. Do you happen to recall your sorce for this information?